Image Quality, Artifacts and Hazards in Imaging. Laura Gruber, MBA, RT(R), RDMS, RVT Sr. Director Medical Imaging

Transcription

1 Image Quality, Artifacts and Hazards in Imaging Laura Gruber, MBA, RT(R), RDMS, RVT Sr. Director Medical Imaging

2 Case 1 2

3 Case 1 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a thermoregulating blanket Case Courtesy of Judy Le, R.T. (CT) (R) 3

4 Case 1 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a thermoregulating blanket Case Courtesy of Judy Le, R.T. (CT) (R) 4

5 Case 1 Key Concepts: 1.) Thermo-regulating blankets can cause honey-comb like artifacts if they are left in place during xray. These artifacts do not obscure visibility of lines, however, they can be distracting when evaluating bowel gas and potential free air. 3.) When evaluating lines and lungs, thermoregulating blankets are acceptable to leave in if patient condition prohibits removal. If evaluating pathology in the abdomen, artifacts caused by these blankets may affect diagnostic interpretation. Case Courtesy of Judy Le, R.T. (CT) (R) 5

6 Case 2 6

7 Case 2 What is the image quality issue in this picture? A.) Baby should be prone B.) Immobilization board will create significant artifact C.) Lead shield in the fluoroscopic field of view D.) Using an image intensifier instead of flat panel fluoroscope 7

8 Case 2 What is the image quality issue in this picture? A.) Baby should be prone B.) Immobilization board will create significant artifact C.) Lead shield in the fluoroscopic field of view D.) Using an image intensifier instead of flat panel fluoroscope 8

9 Case 2 Key Concepts: 1.) All modern fluoroscopes uses automatic brightness control (ABC) which means the machine adjusts the xray tube output based on how much attenuation it detects. 2.) A lead gonad shield in the fluoroscopy field of view will cause the fluoroscopy system to substantially increase radiation to the patient AND compromise image quality. 3.) You should also not use lead shields in the field of view for other modalities that use automatic exposure control (ex. xray=phototiming, CT=dose modulation) 9

10 Case 3 10

11 Case 3 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device 11

12 Case 3 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device 12

13 Case 3 Key Concepts: 1.) Scoliosis exams are often performed with a series of 2 or 3 images exposing the same detector in rapid succession. 2.) Though rare, the burn-in artifact can be seen in high mas scoli exams, it is most often noted as a repeated image of the xray marker. 13

14 Case 4 14

15 Case 4 What is the image quality issue in this picture? A.) Use of Lap Shield B.) Room is not suitable for portable xray imaging C.) Source-to-image distance is too short D.) Portable xray tube should be under the table. 15

16 Case 4 What is the image quality issue in this picture? A.) Use of Lap Shield B.) Room is not suitable for portable xray imaging C.) Source-to-image distance is too short D.) Portable xray tube should be under the table. 16

17 Case 4 There is a ruler provided to help you determine the SID 17

18 Case 4 Key Concepts: 1.) Portable xray protocols have defined SID s, make sure you try to approximate the correct distance so the dose is appropriate and the image quality is consistent. 2.) Use the ruler provided by the system and pick the appropriate protocol (27, 40, or 72 ) 18

19 Case 5 19

20 Case 5 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device Case Courtesy of Judy Le, R.T. (CT) (R) 20

21 Case 5 What is the image quality issue in this picture? A.) Improper exposure/technique B.) Detector burn-in or ghosting artifact C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device Case Courtesy of Judy Le, R.T. (CT) (R) 21

22 Case 5 Key Concepts: 1.) Gel pillows are filled with a non-toxic water based gel that can provide the support needs of micro-preemie, preemie, and full-term infants 2.) Removal of gel pillows is highly recommended for any indication. Artifacts caused by gel pillows can mimic pathology, such as free air, which can lead to misinterpretation by Radiologists. 3.) These gel positioning devices can lead to additional x-rays to confirm artifact vs. pathology, resulting in increased radiation dose to the patient. Case Courtesy of Judy Le, R.T. (CT) (R) 22

23 Case 6 23

24 Case 6 What is the image quality issue in this picture? A.) Chest chair is too large B.) Baby should have arms down C.) Holding is never acceptable in pediatric radiology D.) Poor collimation 24

25 Case 6 What is the image quality issue in this picture? A.) Chest chair is too large B.) Baby should have arms down C.) Holding is never acceptable in pediatric radiology D.) Poor collimation 25

26 Case 6 Key Concepts: 1.) Poor collimation is a source of poor image quality in digitally processed images. 2.) Differences in collimation introduces variability in the source images and inconsistent results on processed images. 2.) Collimation is also very effective at reducing our patient s exposure (and it also reduces the exposure of anyone who is holding the child). Always collimate as much as reasonable! 26

27 Case 7 27

28 Case 7 What is the image quality issue in this picture? A.) Patient should be feet first first B.) Patient is off iso-center C.) Incorrect pediatric table insert in place D.) Incorrect position on the table in the head-to-foot direction 28

29 Case 7 What is the image quality issue in this picture? A.) Patient should be feet first first B.) Patient is off iso-center C.) Incorrect pediatric table insert in place D.) Incorrect position on the table in the head-to-foot direction 29

30 Case 7 Automatic dose control requires good isocentering. 30

31 Case 7 Magnification = SID/SOD 31

32 Z-axis dose modulation Bushberg JT, et al. The Essential Physics of Medical Imaging, Wolters Kluwer, Philadelphia, 3 rd Edition,

33 Z-axis dose modulation Bushberg JT, et al. The Essential Physics of Medical Imaging, Wolters Kluwer, Philadelphia, 3 rd Edition,

34 Case 7 Key Concepts: 1.) Use your lasers to ensure very good centering of the patient in the AP and RL directions. 2.) If you do notice you are off-isocenter, do not move your planning box to accommodate. Go back in the room and physically reposition your table and acquire another topogram. 34

35 Case 8 35

36 Case 8 What is the image quality issue in this picture? A.) Cosmetics containing glitter may lead to tissue heating and discomfort during MRI B.) Cosmetics containing glitter may lead to imaging artifacts in MRI C.) Glitter tattoos can lead to bright spots in the MRI image D.) Both A and B 36

37 Case 8 What is the image quality issue in this picture? A.) Cosmetics containing glitter may lead to tissue heating and discomfort during MRI B.) Cosmetics containing glitter may lead to imaging artifacts in MRI C.) Glitter tattoos can lead to bright spots in the MRI image D.) Both A and B 37

38 Case 8 38

39 Case 8 39

40 Case 8 40

41 41

42 Case 9 42

43 Case 9 What is the image quality issue in this picture? A.) Artifact due to patient motion B.) Iterative reconstruction artifact C.) Artifact due to contrast extravasation D.) Ring artifact from detector failure 43

44 Case 9 What is the image quality issue in this picture? A.) Artifact due to patient motion B.) Iterative reconstruction artifact C.) Artifact due to contrast extravasation D.) Ring artifact from detector failure 44

45 Case 9 Key Concepts: 1.) Contrast extravasation means that the scan quality will be compromised and possibly non-diagnostic. 2.) Always check with an attending before continuing a scan where extravasation is suspected. 45

46 Case 10 46

47 Case 10 What is the image quality issue in this picture? A.) Post-processing error B.) Improper exposure/technique C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3 47

48 Case 10 What is the image quality issue in this picture? A.) Post-processing error B.) Improper exposure/technique C.) Electromagnetic interference artifact (EMI) D.) Artifact from a positioning device TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3 48

49 Case 10 Key Concepts: 1.) Some devices such as this thermoregulation unit can interfere electromagnetically with digital detectors. 2.) Electromagnetic interference artifacts often manifest as parallel lines and can be eliminated if the source of the interference can be removed or turned off. TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3 49

50 Case 10 Thermoregulation Unit ON Thermoregulation Unit OFF TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3 50

51 Case 11 51

52 Case 11 What is the hazard or compliance issue in this picture? 52

53 Case 11 Answer: Objects depressing the fluoroscopy foot-pedal! 53

54 Case 11 Key Concepts: 1.) Always remember to practice safety with foot-pedal operated devices. Keep them clear of equipment which can fall on to the pedal. Inhibit xrays if possible when the device is not in use. 2.) Become familiar with the beam-on alerts for your device, both visual and audio. 3.) Always wear your radiation badge in case of unexpected exposures. 54

55 Case 12 55

56 Case 12 What is the hazard or compliance issue in this picture? 56

57 Case 12 Answer: Someone ripped off the spacer cone! 57

58 Case 12 Answer: The spacer cone is there to protect the patient s skin. 58

59 Case 12 Key Concepts: 1.) Never remove the spacer cone. This is in place to ensure the entrance skin dose to the patient is not too high and is regulated by the State and Joint Commission. 2.) Remember that the xray radiation is highest directly at the tube output and decreases by 1/distance^2. Entrance skin dose is highest if anatomy is closer to tube output, so the spacer cone is there to reduce the likelihood of skin burns. 59

60 Case 13 60

61 Case 13 What is the hazard or compliance issue in this picture? 61

62 Case 13 Answer: This physician is entering the MRI room with his pager and stethoscope! 62

63 Case 13 Key Concepts: 1.) Most metal object MRI accidents occur because of untrained or absent-minded people entering with common items. 2.)As the most trained staff in the hospital, it s our job to always be vigilant with screening (even if it is a doctor or supervisor who is entering the MRI room). 63

64 Case 14 64

65 Case 14 What is the hazard or compliance issue in this picture? 65

66 Case 14 Answer: A magnet quench may cause vaporized helium (a white smoky substance) to fill the MRI scanner room. 66

67 Case 14 MRI scanners are built with a exhaust for vaporized helium. 67

68 Case 14 Example of vaporized helium exhaust from a quench. Failure of the exhaust system can lead to very high gas pressures in the scanner room. 68

69 Case 14 Key Concepts: 1.) MRI system use superconducting technology that must be kept at cryogenic temperatures. Any disturbance to this cryo system can lead to a quench. 2.) Quenches happen more often than you might think. Generally there is a audible loud bang, an immediate loss of field strength, and the room will fill with helium gas. 2.)Immediately evacuate all personnel from the area to avoid breathing in helium vapor and contact HTM. 69

70 Case 15 70

71 Case 15 What is the hazard or compliance issue in this picture? 71

72 Case 15 Answer: Drinking cups in the Nuclear Medicine Hotlab! 72

73 Case 15 Key Concepts: 1.) Eating, drinking, applying cosmetics or creams can introduce radio-isotopes to your body and lead to internal exposure. 2.) Refrain from these activities in all radioactive material work areas and avoid touching your eyes, nose, and lips. 73

74 Case 16 74

75 Case 16 What is the hazard or compliance issue in this picture? 75

76 Case 16 Answer: This staff member is standing in the highest radiation scatter zone! 76

77 Case 16 Scatter profile for CT scanners is forward along the table. 77

78 Case 16 The side of the CT scanner has lower scatter and is a preferable place to stand than next to the table. 78

79 Case 16 Key Concepts: 1.) The CT scanner tend to throw radiation forward and backward along the length of the patient bed. 2.) If possible, it s better for staff and family member to sneak around to the side of the scanner during the acquisition to reduce their own exposure. 79

80 Case 17 80

81 Case 17 What is the hazard or compliance issue in this picture? 81

82 Case 17 Answer: Staff member is using frontal apron but has back turned to source of radiation! 82

83 Frontal Drop Lead Apron Type 83

84 Skirt Vest Type Apron 84

85 Case 17 Key Concepts: 1.) Be careful if you are wearing a front apron that you are facing the source of radiation and do not get your body rotated. 2.) Wear a skirt/vest style apron in circumstances when you cannot always face the procedure (ie. if you are circulating). 3.) If you have no other option, wear two front lead aprons, one front-ward, the other back-ward to protect your organs from all sides. 85

86 Acknowledgements Jackie Choragwicki Merima Karastanovic Judy Le THANK YOU! Christina L. Sammet, Ph.D., DABR Medical Physicist Radiation and Laser Safety Officer 86